Method of manufacturing formed article, covering member, and forming apparatus comprising the same

Abstract

The present invention relates to a method of manufacturing a formed article forming an upper surface of a forming material comprised of a thermosoftening substance into a desired shape by positioning the forming material on a forming surface of a mold and heating the forming material to a temperature permitting deformation to bring a lower surface of the forming material into tight contact with the forming surface. The forming is conducted while an exposed portion on the forming surface side of the mold upon which the forming material has been positioned is covered with a covering member. The present invention further relates to a covering member and a forming apparatus. According to the present invention, formed articles with a desired shape can be formed with high accuracy by preventing the contamination of upper surface of forming materials by foreign matter during forming.

1. A method of manufacturing a formed article, wherein the formed article is a casting mold or a portion of a casting mold for the manufacture of a progressive dioptric power eyeglass lens, the method comprising:
 positioning a forming material comprising a thermosoftening substance on a forming surface of a mold, wherein the forming material has an upper surface and a lower surface, and the forming surface of the mold has a free-form shape; and 
 heating the forming material to a temperature permitting deformation, resulting in bringing the lower surface of the forming material into tight contact with the forming surface, whereby the upper surface of the forming material is formed into a free-form optical surface to form the casting mold or a portion of the casting mold for the manufacture of a progressive dioptric power eyeglass lens; wherein the forming is conducted while an exposed portion on the forming surface side of the mold upon which the forming material has been positioned is covered with a covering member; 
 and the mold has through-holes having a diameter in the range of 0.3 to 0.5 mm and the through-holes are provided such that positions corresponding to reference points for measurement of a dioptric power of the progressive dioptric eyeglass lens on the lower surface of the forming material do not overlap openings on the forming surface side when the forming surface and the lower surface of the forming material are brought into tight contact. 
 
     
     
       2. The method of manufacturing a formed article according to  claim 1 , wherein the covering member has a thermal conductivity ranging from 3 to 170 W/mk. 
     
     
       3. The method of manufacturing a formed article according to  claim 1 , wherein the covering member is comprised of a ceramic material. 
     
     
       4. The method of manufacturing a formed article according to  claim 3 , wherein the ceramic material has a porosity ranging from 30 to 40 percent. 
     
     
       5. The method of manufacturing a formed article according to  claim 3 , wherein an upper inside surface of the covering member has been subjected to processing to prevent particle scattering, and wherein the processing comprises applying a glaze to the upper inside surface of the covering member after press molding of the covering member, but before sintering of the covering member. 
     
     
       6. The method of manufacturing a formed article according to  claim 1 , wherein
 the covering member has a protruding part on an inner lateral surface thereof, 
 the forming material is positioned on the forming surface of the mold in a state where the protruding part contacts with a lateral surface of the forming material at least at a portion thereof. 
 
     
     
       7. The method of manufacturing a formed article according to  claim 1 , wherein the covering member has an opening and an edge surface of the opening is a smooth surface. 
     
     
       8. The method of manufacturing a formed article according to  claim 1 , wherein an upper inside surface of the covering member is roughly similar in shape to the shape of the upper surface of the forming material or a roughly flat surface. 
     
     
       9. The method of manufacturing a formed article according to  claim 1 , wherein the mold has a plurality of through-holes running from the forming surface to an opposite surface from the forming surface, and comprising application of suction through the through-holes during the forming.